The front bezel is still attached to the iMac by the microphone cable.

Gently lift the front bezel from its top edge off the rear case. It helps to use your thumbs to push down very gently on the corners of the display.

Once the top edge of the front bezel has cleared the rear case, rotate the front bezel toward the stand and lift it off the rear case.

When reinstalling the front bezel, start at the lower edge and make sure it is flush with the rear case before lowering the top edge onto the iMac.